JP2014515323A - Method for joining a thermoplastic polymer to a thermosetting polymer part - Google Patents

Abstract

The present invention relates to a method of joining a thermoplastic polymer having a melting point above the curing temperature of a thermosetting polymer to a thermosetting polymer component. The method includes the following steps. A thermoset polymer part to be cured comprising at least a portion to be joined with an implant made of a thermoplastic polymer, a portion to be brought into contact with at least a portion to which the thermoplastic polymer is joined, and a thermoplastic assembly; Heating to the melting point of the polymer, thereby melting the thermoplastic polymer constituting the implant to fuse with the thermoplastic polymer and cooling the assembly. In the present invention, the thermoplastic polymer has a melting point that exceeds the curing temperature of the thermosetting polymer, and the thermosetting polymer has a melting point during the joining step at the joint portion of the implant with the thermosetting polymer component. The implant is designed so that heating above the maximum service temperature is avoided.
[Selection] Figure 1

Description

  The present invention relates to a method of joining a thermoplastic polymer to a thermosetting polymer part. The present invention also relates to a method of joining a thermoset polymer part to another thermoset polymer part. The present invention further relates to a cured thermoset polymer part having a thermoplastic polymer implant in at least a portion of the part to which the thermoset polymer part is joined, and further to a bondable surface. It relates to a non-thermoset or partially thermoset thermoset polymer part having an implant made of a thermoplastic polymer that forms. The present invention further relates to an assembly of a cured thermoset polymer component having a thermoplastic surface and a thermoplastic polymer component welded thereto.

  Thermoplastic (fiber reinforced) polymers containing oligomers are increasingly used as structural materials because of their potential for recycling. The thermoplastic polymer can be softened by heating (amorphous thermoplastic) or ultimately melted (semi-crystallized thermoplastic). Then, it will be in a solid state by cooling it. The physical changes caused by such temperatures are generally reversible, making thermoplastic polymers recyclable. In solid amorphous thermoplastics, polymer molecular chains are randomly arranged, whereas in solid semi-crystalline thermoplastics, some of them are regularly arranged as crystallized regions. The molecular chain of the polymer is included. In the present invention, even if the term “melting” or “melt” is used, it is not limited to one type of thermoplastic polymer. Thermoplastic polymers undergo progressive softening when heated above the glass transition temperature (Tg). At temperatures substantially above the glass transition point, amorphous thermoplastics behave like high viscosity liquids, whereas semi-crystalline polymers remain solid at this temperature range. The semi-crystallized thermoplastic material exhibits a melting point (Tm) at which the material melts when it exceeds this (melting point) and behaves like a liquid. The viscosity decreases rapidly with further temperature rise.

  Thermosetting polymers are typical cross-linked polymers and are composed of resins such as epoxides (often referred to as epoxies), bismaleimides, unsaturated polyesters, and vinyl ester polymers. Thermosetting polymers typically include a resin (monomer) and a curing agent that cooperate to form a crosslinked polymer prior to curing. Curing may be designed to occur at room temperature or higher (typically between 80 ° C. and 200 ° C.). Upon curing, the monomer and curing agent react and the viscosity of the mixture is until the state becomes a cross-linked solid polymer that is not reversible with temperature change unless the thermosetting polymer is degraded at a temperature above its degradation temperature. To increase. After curing, the thermosetting polymer also exhibits a glass transition temperature above which it causes considerable softening of the thermosetting polymer and behaves like a rubber.

  The polymer composite includes fibers or particulate reinforcements embedded in a matrix polymer that can be either thermoset or thermoplastic. Known polymer composites include polyester resins reinforced with glass fibers and epoxy resins reinforced with carbon fibers. Since these composite materials use a thermosetting polymer as a substrate, they are often called thermosetting composite materials.

  One major drawback of thermosetting (composite) polymers is that they usually cannot be welded. This is because thermosetting polymers cannot be melted and cannot be resolidified by raising or lowering the temperature. Thermoset (composite) polymers are typically bonded to other parts by methods that have the disadvantages of both adhesive bonding or bolting. Adhesive bonding is expensive and sometimes harmful to the environment, and the quality of the bonding is usually sensitive to changes in process parameters. On the other hand, bolting creates holes in the parts to be joined, which creates stress concentrations and the possibility of initial failure.

  There is a need for a wider range of thermosetting polymers or thermosetting polymer composites that can be joined by welding to other thermosetting polymers or thermosetting polymer composites or thermoplastic polymers (composites). .

  The present invention relates to a method for bonding a thermosetting polymer (composite) part to another thermosetting polymer part, a thermosetting polymer having a thermoplastic implant that provides a thermally bondable surface. It is provided by using (composite material).

  The present invention further provides a cured thermoset polymer part comprising a thermoplastic polymer implant at least in the part of the thermoset polymer part to be joined and the thermoplastic forming a bondable surface. An uncured or partially cured thermoset polymer part with a polymeric implant is provided.

  The present invention also provides an assembly of cured thermoset polymer parts having a thermoplastic surface and a thermoplastic polymer.

  The present invention further includes an uncured or partially cured thermoset polymer part having a thermoplastic polymer (part) that forms a thermally bondable surface, a thermoplastic surface and a thermoplastic that is weldable thereto. An assembly of a cured thermoset polymer composite having a polymer composite.

According to a first aspect, the present invention is a method of joining a thermoplastic polymer (part) to a thermosetting polymer part, the thermoplastic polymer having a melting point above the curing temperature of the thermosetting polymer, The method includes the following steps.
a) providing a thermoplastic polymer;
b) Uncured or partially cured having a curing temperature below the melting point of the thermoplastic polymer and comprising a thermoplastic polymer implant in at least the joined part of the thermosetting polymer part Providing a thermosetting polymer part;
c) placing the thermoplastic polymer in contact with at least the part to be joined;
d) heating the thermoplastic polymer and the thermosetting polymer part to the melting point of the thermoplastic polymer, whereby the thermoplastic polymer constituting the implant melts and fuses with the thermoplastic polymer; The uncured thermosetting polymer part and the thermoplastic polymer implant at least partially interpenetrate;
e) cooling the assembly of the thermoplastic polymer and the cured thermoset polymer part to join the thermoplastic polymer to the cured thermoset polymer part. It should be noted that the thermoplastic polymer has a melting point that exceeds the curing temperature of the thermosetting polymer part, but the interface of the implant with the thermosetting polymer part is thermoset during the joining step d). The implant is designed so that heating beyond the maximum use temperature of the functional polymer is avoided.

  The maximum use temperature of the polymer (composite material) is well known to those skilled in the art and is generally given by the supplier.

  In the method according to the invention, the thermoplastic polymer implant acts as a heat sink for the thermosetting polymer (composite) part. This allows heat added to the melt of the thermoplastic polymer to be joined and the thermoplastic embedding polymer that makes up the implant to be present in the welded joint where it is substantially welded. Absorbed by melting of the thermoplastic polymer comprising the inclusion. According to the present invention, even when heating exceeds such a degradation temperature (of the thermosetting polymer), the temperature at the joint between the implant and the thermosetting polymer (composite material) component is substantially reduced. The temperature gradient during thermal bonding by welding is maintained in the thermoplastic implant so that it is sufficiently low without degrading the thermosetting polymer. This avoids excessive heating at the joint between the thermosetting polymer (composite material) and the implant, thus giving the possibility of joining the thermoplastic polymer to the thermosetting polymer part by welding. The thermoplastic polymer has a melting point that exceeds the curing temperature of the thermosetting polymer.

  The above advantages are particularly beneficial for aerospace and aircraft applications where it is determined to use a thermoplastic polymer having a relatively high melting point due to the relatively high service temperature.

  In the method according to an embodiment of the invention, the heat capacity per unit length of the implant, denoted J / ° K / m, is greater than the heat per unit length given to the assembly during step d). In other words, the implant positioning and cross-sectional dimensions, as well as the thermoplastic polymer making up the implant, are selected to meet the above requirements. The heat per unit length given to the assembly during step d), in particular the heat of welding per length, is also material specific, the welding method used, the specific heat capacity of the material to be welded, its conductivity, And depends on various factors such as the time required to remain molten to obtain a well consolidated material after local heating or local welding. The welding heat per length can be easily determined experimentally by those skilled in the art.

  In a method in another embodiment of the present invention, the heat sink is applied to a portion of the implant, more preferably to the exterior of the implant, and most preferably to the outer edge of the implant. Suitable heat sinks include materials such as blocks, strips, bars, and typically a material having a relatively high specific heat capacity is used as the heat sink material. Suitable materials include metals. The joint portion between the heat sink and the embedded material may further include, for example, a heat absorbing paste. The heat sink is removed after bonding.

  The implant of the thermosetting polymer part preferably comprises reinforcing fibers. However, in another embodiment of the present invention, the implant comprises reinforcing fibers that extend into the thermoset polymer. Such embodiments can reduce welding heat and / or time, thereby obtaining sufficient bond strength while avoiding degradation during the joining of thermoplastic and / or thermosetting polymers. Can do.

  In a method according to another aspect of the invention, it is provided to join another thermosetting polymer part to a thermosetting polymer part. Here, the method is provided in the form of a cured thermoset polymer part comprising a thermoplastic polymer implant in the thermoplastic polymer.

  According to yet another aspect of the present invention, the cured thermoset polymer part comprises an implant made of a thermoplastic polymer at least where the thermoset polymer part is joined.

  In a method according to a preferred embodiment according to the first aspect of the invention, the implant is designed to avoid excessive heating at the joint between the implant and the thermosetting polymer part.

  In a method according to another preferred embodiment of the present invention, the thermosetting polymer part comprises a fiber reinforced thermosetting composite part.

  Furthermore, according to another preferred embodiment of the method according to the invention, the thermosetting polymer part is an assembly of a pre-impregnated thermosetting polymer composite tape laminate and the implant is pre-impregnated. Includes a laminate of thermoset polymer composite tape.

  A further embodiment of the method according to the invention relates to a method wherein the thermoplastic polymer to be joined is a thermoplastic polymer part or a part that is compatible with the thermoplastic polymer surface.

  The thermoplastic polymer to be joined and / or the thermoplastic polymer constituting the implant used in another preferred embodiment of the method according to the invention is selected from the class of engineering thermoplastic polymers having a melting point of at least 200 ° C. Yes. Further, according to a more preferred method, the thermoplastic polymer to be joined and / or the thermoplastic polymer constituting the implant is polyetherimide (PEI), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), Selected from polyetherketone (PEK), polyetherketoneketone (PEKK) and combinations thereof or equivalents thereof.

  Another embodiment of the method according to the invention is characterized in that the thermoplastic polymer to be joined or the thermoplastic polymer constituting the implant contains conductive particles for local heating.

  In one embodiment of the method according to the invention, the thermosetting polymer comprises a hardener mixture of an epoxy resin and / or a bismaleimide resin and a curing agent.

  Uncured or partially cured thermoset polymer parts having thermoplastic polymer implants that form connectable surfaces are laminated pre-impregnated thermoset polymer composite tapes and laminates to form implants It can be conveniently made with pre-impregnated thermoplastic polymer composite tape. Thermoplastic implants can also be produced in situ using an injection method. Simultaneous injection of thermosetting polymer and thermoplastic polymer is also possible.

  The thermosetting polymer part comprising an implant is preferably a thermoplastic polymer (part), or other thermosetting polymer comprising an implant by welding to other thermosetting polymers or thermosetting polymer composites Bonded to a part or thermoplastic polymer (composite material).

  Preferred welding methods include, but are not limited to, induction welding, resistance welding, and laser welding.

  In another aspect of the present invention, an assembly of a cured thermoset polymer part having a thermoplastic surface and a thermoplastic polymer part bonded thereto is provided. Here, the thermoplastic polymer has a melting point exceeding the curing temperature of the thermosetting polymer.

  In any of the above embodiments of the present invention, the thermoplastic polymer implant and the uncured thermoset polymer or thermoset polymer composite adjacent to the implant are thermoset when heated. The curing polymer can be at least partially interpenetrated before curing, thereby allowing the thermoplastic polymer implant to join the thermosetting polymer or thermosetting polymer composite. This ensures that the thermoplastic surface provided to the thermoset polymer (composite) by the implant cannot be easily detached from the thermoset polymer or thermoset polymer composite. Yes.

  A cured or uncured thermoset polymer or thermoset polymer composite with a thermoplastic implant may be further joined to the thermoplastic polymer by the method of the present invention, and the thermoplastic It may be joined to a second thermosetting polymer or thermosetting polymer composite with an implant.

  A further advantage of the invented method is that it provides a high thermoplastic polymer flow when the molten thermoplastic polymer to be joined and the thermoplastic polymer making up the implant are in contact with each other, thereby being joined. Filling any irregularities or defects on the contact surface. This thermoplastic flow is affected by changing the temperature and / or by applying more contact pressure to the parts to be joined, upon heating and allowing additional time for joining.

  The advantages of the method according to the invention may further be that the parts that have been previously joined together may be disassembled or reassembled when needed, which merely at least partially removes the welded thermoplastic and thermoplastic implant. It is related to the fact that it can be done by reheating it. If necessary, additional thermoplastic polymer may be added between the surfaces to be joined for better joining. Reheating can also be used to improve the quality of the welded product in selected areas if necessary.

  In general, the method according to the invention is carried out at a temperature above the glass transition point of the thermoset polymer or polymer composite part to be cured, at least at the joint between the thermoplastic polymer implant and the thermoset polymer. . However, the bond may include a temperature slightly higher than this temperature, or may be close to the degradation temperature of the thermosetting polymer.

  Thermoset polymer (composite) parts may include other parts such as metal implants, foams or honeycomb cores, thermoset parts or film thermoplastics, etc. They may be joined by methods other than the invention, or any other material may be incorporated as an integral part of the thermoset material (composite material) part.

  The present invention will be described in detail below by way of example, using the accompanying drawings for reference, but not limited thereto.

1 is a schematic diagram illustrating a first embodiment according to the present invention consisting of a cured thermoset polymer part having a thermoplastic surface and a thermoplastic polymer part welded thereto; FIG. FIG. 4 is a schematic diagram illustrating a second embodiment according to the present invention consisting of a cured thermoset polymer part having a thermoplastic surface and a thermoplastic polymer part welded thereto. FIG. 5 is a schematic diagram illustrating another embodiment according to the present invention consisting of a cured thermoset polymer part having a thermoplastic surface and a thermoplastic polymer part welded thereto. 1 is a schematic diagram schematically illustrating an embodiment of a thermoplastic implant used in the method of the present invention. FIG.

  Referring to FIG. 1, there is shown an embodiment of an assembly 1 of a cured thermoset polymer part 2 comprising a thermoplastic surface 3, to which a thermoplastic polymer part 4 is welded by the method shown in the present invention. can do. The thermoplastic polymer making up the thermoplastic polymer part 4 has a melting point between 250 ° C. and 400 ° C., which is a thermosetting temperature range typically between about room temperature and 200 ° C. The curing temperature of the thermosetting polymer used for the heat-resistant polymer part 2 is exceeded. The assembly 1 is obtained by the following method. At least the part to which the thermosetting polymer part is to be joined, i.e. in this case the uncured or partly cured thermosetting polymer with a thermoplastic polymer implant 5 on the surface 3 (of the part to be cured 2 Providing a precursor) and curing the thermosetting polymer so that the thermoplastic polymer comprising the uncured thermosetting polymer part 2 and the implant 5 is at least partially interleaved with each other. To penetrate. This step forms a bond between the thermoplastic polymer implant 5 and the thermosetting polymer 2 to be cured. Due to the temperature rise during curing, the thermosetting monomers actually migrate easily to the thermoplastic polymers that make up the implant 5, in particular to their crystalline domains. According to this method, a strong bond is formed between the two. Of course, the curing temperature and time cycle are preferably selected so that the thermosetting monomer (and the curing agent) can move sufficiently deep into the melted polymer of the implant 5. Providing a thermosetting polymer 2 having a thermoplastic implant 5 may be performed without modification of the curing cycle recommended by the manufacturer for that thermosetting polymer 2. However, slight modifications may be required, particularly when the compatibility between the thermosetting polymer 2 and the thermoplastic polymer of the implant 5 is not optimal.

  According to the invention, the thermoplastic polymer (part) 4 is brought into contact with at least the surface 3 of the assembly 1, and the thermoplastic polymer and the thermosetting polymer part are heated to the melting point of the thermoplastic polymer 4, thereby The thermoplastic polymer constituting the implant 5 melts and fuses with the thermoplastic polymer (part) 4. In other words, a bond is formed between the thermoplastic polymer implant 5 and the thermoplastic polymer (part) 4, and this bond of the assembly 1 of the thermoplastic polymer 5 and the cured thermoset polymer part 2. Strengthened by cooling.

  In order to avoid excessive heating of the thermosetting polymer during the joining process, the weld area must be selected according to the geometry of the thermoplastic implant 5. In FIG. 1, the weldable area is schematically indicated by area 6. Heating this region 6 can be done at the melting point of one or both of the thermoplastic polymers 4 and 5. These polymers 4 and 5 preferably differ in melting point by 20 ° C, more preferably differ by 15 ° C, and most preferably differ by 10 ° C. Preferably, the thermoplastic polymers 4 and 5 are substantially the same polymer. The thermoplastic polymer comprising the implant 5 is preferably formed by forming a semi-interpenetrating polymer network upon curing of the thermosetting polymer 2 (shown in FIG. 1). Joined at the internal interface (as in the example shown) or joined at the external interface of the thermosetting polymer 2 (as in the example shown in FIG. 2). To achieve this objective, the thermoplastic polymer 5 is preferably compatible with the selected thermosetting monomer of the thermosetting polymer 2. Those skilled in the art of polymer science have sufficient means at their disposal, such as the well-known thermodynamic criteria and melt criteria.

  Typical joint strengths achievable with the method according to the invention are over 30 MPa, more preferably over 35 MPa, most preferably over 40 MPa (double lap joint strength test )by).

  The general welding pressure range is 50 kPa to 1 MPa, and 100 kPa to 350 kPa is recommended. However, the method according to the invention can provide a good bond even when no pressure is applied. However, pressures in excess of 1 MPa may also be used. Nonetheless, such pressure may cause some squeezing to the molten thermoplastic.

  Another embodiment of an assembly 1 of a cured thermoset polymer part 2 having a thermoplastic surface 3 that can be welded to a thermoplastic polymer part 4 according to the method of the present invention is shown in FIG. In this case, the thermoplastic polymer implant 5 is actually bonded to the outer surface of the thermosetting polymer part 2. However, according to the present invention, when the weldable region of the implant 5 is limited to the region 6, excessive heating of the thermosetting polymer at the joint with the implant 5 is avoided. Since the implant 5 is dimensioned, its function is maintained.

  The thermosetting polymer 2 with the thermoplastic polymer embedding 5 may be joined to the thermoplastic part 4 under external heat and pressure, such as a heated plate. Alternatively, even local heating elements or even heatable materials incorporated in the parts to be joined may be used to allow heat to concentrate on the weld zone 6.

  According to the method according to the invention, heating occurs above the melting point of the thermoplastic polymers 4 and 5, and these thermoplastics exhibit a substantial flow during welding even at relatively low welding pressures. This flow fills the small irregularities in the surfaces of the thermoplastics 4 and 5 or even the relatively small gap between the parts 2 and 4 to be joined.

  Yet another embodiment of an assembly 1 of a cured thermoset polymer part 2 having a thermoplastic surface 3 that can be welded to the thermoplastic polymer part 4 according to the method of the present invention is shown in FIG. In this case, the thermoplastic polymer implant 5 comprises two heat sinks 10 and 11 at the outer edges. When the weldable region is limited to region 6, so that the heating of the thermosetting polymer 2 with the implant 5 at the joint 7 is limited so as not to exceed the maximum use temperature of the thermosetting polymer, The implant 5 is dimensioned. The heat sinks 10 and 11 absorb part of the welding heat. The heat sinks 10 and 11 are attached to the implant 5 using a layer of heat absorbing paste 8. The thermosetting polymer 2 with the thermoplastic polymer implant 5 is joined to the thermoplastic part 4 by using the welding torch 9 in contact with the welded portion 4 in the contact area 6.

  FIG. 4 shows a schematic side view of a preferred implant finally used in the method of the present invention. In the embodiment shown, an implant of thermoplastic polymer is provided, comprising continuous reinforcing fibers 12 extending to the boundary (50, 51) of the implant 5. When such an implant with a thermoset polymer part solidifies, the free (dry) portions of the fibers 12 extend into the thermoset polymer, where these fiber portions are impregnated with the thermoset polymer once. Integrated with the cured thermoset polymer part. The implant according to this embodiment will prove particularly useful in the method of the invention. This is because it provides sufficient bond strength while limiting the heat applied during bonding.

  The method according to the invention further allows to remove and separate the previously welded parts 2 and 4. The parts (2, 4) are then heated at a temperature above the melting point of the thermoplastic polymer (4, 5) and both parts (2, 4) are at least partially separated, but this is not the case. The required power is only needed. Each part (2, 4) then retains most of its surface properties, and the separated parts may then be welded again according to the invented method. If necessary, additional thermoplastic material may be added to the surface of the thermoplastic material to be joined, in which case insufficient thermoplastic material can be utilized for joining.

  The assembly 1 joined according to the present invention provides improved chemical resistance, improved durability and erosion resistance, improved biocompatibility, improved friction, and such further advantages. .

  Since the invention disclosed in the detailed description is provided by way of illustration only, it will be appreciated that numerous variations are envisioned by those skilled in the art within the scope of the appended claims.

  The present invention relates to a method of joining a thermoplastic polymer to a thermosetting polymer part. The present invention also relates to a method of joining a thermoset polymer part to another thermoset polymer part. The present invention further relates to a cured thermoset polymer part having a thermoplastic polymer implant in at least a portion of the part to which the thermoset polymer part is joined, and further to a bondable surface. It relates to a non-thermoset or partially thermoset thermoset polymer part having an implant made of a thermoplastic polymer that forms. The present invention further relates to an assembly of a cured thermoset polymer component having a thermoplastic surface and a thermoplastic polymer component welded thereto.

  Thermoplastic (fiber reinforced) polymers containing oligomers are increasingly used as structural materials because of their potential for recycling. The thermoplastic polymer can be softened by heating (amorphous thermoplastic) or ultimately melted (semi-crystallized thermoplastic). Then, it will be in a solid state by cooling it. The physical changes caused by such temperatures are generally reversible, making thermoplastic polymers recyclable. In solid amorphous thermoplastics, polymer molecular chains are randomly arranged, whereas in solid semi-crystalline thermoplastics, some of them are regularly arranged as crystallized regions. The molecular chain of the polymer is included. In the present invention, even if the term “melting” or “melt” is used, it is not limited to one type of thermoplastic polymer. Thermoplastic polymers undergo progressive softening when heated above the glass transition temperature (Tg). At temperatures substantially above the glass transition point, amorphous thermoplastics behave like high viscosity liquids, whereas semi-crystalline polymers remain solid at this temperature range. The semi-crystallized thermoplastic material exhibits a melting point (Tm) at which the material melts when it exceeds this (melting point) and behaves like a liquid. The viscosity decreases rapidly with further temperature rise.

  Thermosetting polymers are typical cross-linked polymers and are composed of resins such as epoxides (often referred to as epoxies), bismaleimides, unsaturated polyesters, and vinyl ester polymers. Thermosetting polymers typically include a resin (monomer) and a curing agent that cooperate to form a crosslinked polymer prior to curing. Curing may be designed to occur at room temperature or higher (typically between 80 ° C. and 200 ° C.). Upon curing, the monomer and curing agent react and the viscosity of the mixture is until the state becomes a cross-linked solid polymer that is not reversible with temperature change unless the thermosetting polymer is degraded at a temperature above its degradation temperature. To increase. After curing, the thermosetting polymer also exhibits a glass transition temperature above which it causes considerable softening of the thermosetting polymer and behaves like a rubber.

  The polymer composite includes fibers or particulate reinforcements embedded in a matrix polymer that can be either thermoset or thermoplastic. Known polymer composites include polyester resins reinforced with glass fibers and epoxy resins reinforced with carbon fibers. Since these composite materials use a thermosetting polymer as a substrate, they are often called thermosetting composite materials.

  One major drawback of thermosetting (composite) polymers is that they usually cannot be welded. This is because thermosetting polymers cannot be melted and cannot be resolidified by raising or lowering the temperature. Thermoset (composite) polymers are typically bonded to other parts by methods that have the disadvantages of both adhesive bonding or bolting. Adhesive bonding is expensive and sometimes harmful to the environment, and the quality of the bonding is usually sensitive to changes in process parameters. On the other hand, bolting creates holes in the parts to be joined, which creates stress concentrations and the possibility of initial failure.

  WO 2007/109855 discloses a method in which a thermoplastic polymer insert is provided in a molded part of a thermosetting polymer, and the thermoplastic molded part is bonded thereto. Adhesion is the process of bringing the thermoplastic part into contact with the part to be joined and heating the entire thermoplastic part to the melting point, at which time the thermoplastic polymer insert melts and fuses with the thermoplastic part. Is done. Heating is performed by high frequency welding.

  Pratt et al., “Ultrasonic Welding Method for RIM Parts Using Thermoplastic Inserts” (Motorola Technology Development Vol. 27, 1996, May 1, pp. 200-201) also describes RIM nylon parts. Discloses a method of adhering a thermoplastic molded part to a molded part of a thermosetting RIM nylon polymer having a thermoplastic insert and a method of applying ultrasonic welding.

  U.S. Patent Publication No. 2002/0113066 discloses another method of adhering a thermoplastic molded part to a molded part of a thermosetting polymer. The thermosetting molded product portion is obtained by curing together with a thermoplastic material layer to which ferromagnetic fine particles are added. In this method, a bondable surface is generated so as to bond with a thermoplastic molded part by ultrasonic welding.

  International application PCT / AU2007 / 001296, for example, discloses a method for joining a thermoset composite tube with a thermoplastic insert to a thermoplastic connector. Joining is achieved by heating and recooling the thermoplastic resin.

  There is a need for a wider range of thermosetting polymers or thermosetting polymer composites that can be joined by welding to other thermosetting polymers or thermosetting polymer composites or thermoplastic polymers (composites). .

  The present invention relates to a method for bonding a thermosetting polymer (composite) part to another thermosetting polymer part, a thermosetting polymer having a thermoplastic implant that provides a thermally bondable surface. It is provided by using (composite material).

  The present invention further provides a cured thermoset polymer part comprising a thermoplastic polymer implant at least in the part of the thermoset polymer part to be joined and the thermoplastic forming a bondable surface. An uncured or partially cured thermoset polymer part with a polymeric implant is provided.

  The present invention also provides an assembly of cured thermoset polymer parts having a thermoplastic surface and a thermoplastic polymer.

  The present invention further includes an uncured or partially cured thermoset polymer part having a thermoplastic polymer (part) that forms a thermally bondable surface, a thermoplastic surface and a thermoplastic that is weldable thereto. An assembly of a cured thermoset polymer composite having a polymer composite.

According to a first aspect, the present invention is a method of joining a thermoplastic polymer (part) to a thermosetting polymer part, the thermoplastic polymer having a melting point above the curing temperature of the thermosetting polymer, The method includes the following steps.
a) providing a thermoplastic polymer;
b) Uncured or partially cured having a curing temperature below the melting point of the thermoplastic polymer and comprising a thermoplastic polymer implant in at least the joined part of the thermosetting polymer part Providing a thermosetting polymer part;
c) placing the thermoplastic polymer in contact with at least the part to be joined;
d) heating the thermoplastic polymer and the thermosetting polymer part to the melting point of the thermoplastic polymer, whereby the thermoplastic polymer constituting the implant melts and fuses with the thermoplastic polymer; The uncured thermosetting polymer part and the thermoplastic polymer implant at least partially interpenetrate;
e) cooling the assembly of the thermoplastic polymer and the cured thermoset polymer part to join the thermoplastic polymer to the cured thermoset polymer part. It should be noted that the thermoplastic polymer has a melting point that exceeds the curing temperature of the thermosetting polymer part, but the interface of the implant with the thermosetting polymer part is thermoset during the joining step d). The implant is designed so that heating beyond the maximum use temperature of the functional polymer is avoided.

  The maximum use temperature of the polymer (composite material) is well known to those skilled in the art and is generally given by the supplier.

  In the method according to the invention, the thermoplastic polymer implant acts as a heat sink for the thermosetting polymer (composite) part. This allows heat added to the melt of the thermoplastic polymer to be joined and the thermoplastic embedding polymer that makes up the implant to be present in the welded joint where it is substantially welded. Absorbed by melting of the thermoplastic polymer comprising the inclusion. According to the present invention, even when heating exceeds such a degradation temperature (of the thermosetting polymer), the temperature at the joint between the implant and the thermosetting polymer (composite material) component is substantially reduced. The temperature gradient during thermal bonding by welding is maintained in the thermoplastic implant so that it is sufficiently low without degrading the thermosetting polymer. This avoids excessive heating at the joint between the thermosetting polymer (composite material) and the implant, thus giving the possibility of joining the thermoplastic polymer to the thermosetting polymer part by welding. The thermoplastic polymer has a melting point that exceeds the curing temperature of the thermosetting polymer.

  The above advantages are particularly beneficial for aerospace and aircraft applications where it is determined to use a thermoplastic polymer having a relatively high melting point due to the relatively high service temperature.

  In the method according to an embodiment of the invention, the heat capacity per unit length of the implant, denoted J / ° K / m, is greater than the heat per unit length given to the assembly during step d). In other words, the implant positioning and cross-sectional dimensions, as well as the thermoplastic polymer making up the implant, are selected to meet the above requirements. The heat per unit length given to the assembly during step d), in particular the heat of welding per length, is also material specific, the welding method used, the specific heat capacity of the material to be welded, its conductivity, And depends on various factors such as the time required to remain molten to obtain a well consolidated material after local heating or local welding. The welding heat per length can be easily determined experimentally by those skilled in the art.

  In a method in another embodiment of the present invention, the heat sink is applied to a portion of the implant, more preferably to the exterior of the implant, and most preferably to the outer edge of the implant. Suitable heat sinks include materials such as blocks, strips, bars, and typically a material having a relatively high specific heat capacity is used as the heat sink material. Suitable materials include metals. The joint portion between the heat sink and the embedded material may further include, for example, a heat absorbing paste. The heat sink is removed after bonding.

  The implant of the thermosetting polymer part preferably comprises reinforcing fibers. However, in another embodiment of the present invention, the implant comprises reinforcing fibers that extend into the thermoset polymer. Such embodiments can reduce welding heat and / or time, thereby obtaining sufficient bond strength while avoiding degradation during the joining of thermoplastic and / or thermosetting polymers. Can do.

  In a method according to another aspect of the invention, it is provided to join another thermosetting polymer part to a thermosetting polymer part. Here, the method is provided in the form of a cured thermoset polymer part comprising a thermoplastic polymer implant in the thermoplastic polymer.

  According to yet another aspect of the present invention, the cured thermoset polymer part comprises an implant made of a thermoplastic polymer at least where the thermoset polymer part is joined.

  In a method according to a preferred embodiment according to the first aspect of the invention, the implant is designed to avoid excessive heating at the joint between the implant and the thermosetting polymer part.

  In a method according to another preferred embodiment of the present invention, the thermosetting polymer part comprises a fiber reinforced thermosetting composite part.

  Furthermore, according to another preferred embodiment of the method according to the invention, the thermosetting polymer part is an assembly of a pre-impregnated thermosetting polymer composite tape laminate and the implant is pre-impregnated. Includes a laminate of thermoset polymer composite tape.

  A further embodiment of the method according to the invention relates to a method wherein the thermoplastic polymer to be joined is a thermoplastic polymer part or a part that is compatible with the thermoplastic polymer surface.

  The thermoplastic polymer to be joined and / or the thermoplastic polymer constituting the implant used in another preferred embodiment of the method according to the invention is selected from the class of engineering thermoplastic polymers having a melting point of at least 200 ° C. Yes. Further, according to a more preferred method, the thermoplastic polymer to be joined and / or the thermoplastic polymer constituting the implant is polyetherimide (PEI), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), Selected from polyetherketone (PEK), polyetherketoneketone (PEKK) and combinations thereof or equivalents thereof.

  Another embodiment of the method according to the invention is characterized in that the thermoplastic polymer to be joined or the thermoplastic polymer constituting the implant contains conductive particles for local heating.

  In one embodiment of the method according to the invention, the thermosetting polymer comprises a hardener mixture of an epoxy resin and / or a bismaleimide resin and a curing agent.

  Uncured or partially cured thermoset polymer parts having thermoplastic polymer implants that form connectable surfaces are laminated pre-impregnated thermoset polymer composite tapes and laminates to form implants It can be conveniently made with pre-impregnated thermoplastic polymer composite tape. Thermoplastic implants can also be produced in situ using an injection method. Simultaneous injection of thermosetting polymer and thermoplastic polymer is also possible.

  The thermosetting polymer part comprising an implant is preferably a thermoplastic polymer (part), or other thermosetting polymer comprising an implant by welding to other thermosetting polymers or thermosetting polymer composites Bonded to a part or thermoplastic polymer (composite material).

  Preferred welding methods include, but are not limited to, induction welding, resistance welding, and laser welding.

  In another aspect of the present invention, an assembly of a cured thermoset polymer part having a thermoplastic surface and a thermoplastic polymer part bonded thereto is provided. Here, the thermoplastic polymer has a melting point exceeding the curing temperature of the thermosetting polymer.

  In any of the above embodiments of the present invention, the thermoplastic polymer implant and the uncured thermoset polymer or thermoset polymer composite adjacent to the implant are thermoset when heated. The curing polymer can be at least partially interpenetrated before curing, thereby allowing the thermoplastic polymer implant to join the thermosetting polymer or thermosetting polymer composite. This ensures that the thermoplastic surface provided to the thermoset polymer (composite) by the implant cannot be easily detached from the thermoset polymer or thermoset polymer composite. Yes.

  A cured or uncured thermoset polymer or thermoset polymer composite with a thermoplastic implant may be further joined to the thermoplastic polymer by the method of the present invention, and the thermoplastic It may be joined to a second thermosetting polymer or thermosetting polymer composite with an implant.

  A further advantage of the invented method is that it provides a high thermoplastic polymer flow when the molten thermoplastic polymer to be joined and the thermoplastic polymer making up the implant are in contact with each other, thereby being joined. Filling any irregularities or defects on the contact surface. This thermoplastic flow is affected by changing the temperature and / or by applying more contact pressure to the parts to be joined, upon heating and allowing additional time for joining.

  The advantages of the method according to the invention may further be that the parts that have been previously joined together may be disassembled or reassembled when needed, which merely at least partially removes the welded thermoplastic and thermoplastic implant. It is related to the fact that it can be done by reheating it. If necessary, additional thermoplastic polymer may be added between the surfaces to be joined for better joining. Reheating can also be used to improve the quality of the welded product in selected areas if necessary.

  In general, the method according to the invention is carried out at a temperature above the glass transition point of the thermoset polymer or polymer composite part to be cured, at least at the joint between the thermoplastic polymer implant and the thermoset polymer. . However, the bond may include a temperature slightly higher than this temperature, or may be close to the degradation temperature of the thermosetting polymer.

  Thermoset polymer (composite) parts may include other parts such as metal implants, foams or honeycomb cores, thermoset parts or film thermoplastics, etc. They may be joined by methods other than the invention, or any other material may be incorporated as an integral part of the thermoset material (composite material) part.

  The present invention will be described in detail below by way of example, using the accompanying drawings for reference, but not limited thereto.

1 is a schematic diagram illustrating a first embodiment according to the present invention consisting of a cured thermoset polymer part having a thermoplastic surface and a thermoplastic polymer part welded thereto; FIG. FIG. 4 is a schematic diagram illustrating a second embodiment according to the present invention consisting of a cured thermoset polymer part having a thermoplastic surface and a thermoplastic polymer part welded thereto. FIG. 5 is a schematic diagram illustrating another embodiment according to the present invention consisting of a cured thermoset polymer part having a thermoplastic surface and a thermoplastic polymer part welded thereto. 1 is a schematic diagram schematically illustrating an embodiment of a thermoplastic implant used in the method of the present invention. FIG.

  Referring to FIG. 1, there is shown an embodiment of an assembly 1 of a cured thermoset polymer part 2 comprising a thermoplastic surface 3, to which a thermoplastic polymer part 4 is welded by the method shown in the present invention. can do. The thermoplastic polymer making up the thermoplastic polymer part 4 has a melting point between 250 ° C. and 400 ° C., which is a thermosetting temperature range typically between about room temperature and 200 ° C. The curing temperature of the thermosetting polymer used for the heat-resistant polymer part 2 is exceeded. The assembly 1 is obtained by the following method. At least the part to which the thermosetting polymer part is to be joined, i.e. in this case the uncured or partly cured thermosetting polymer with a thermoplastic polymer implant 5 on the surface 3 (of the part to be cured 2 Providing a precursor) and curing the thermosetting polymer so that the thermoplastic polymer comprising the uncured thermosetting polymer part 2 and the implant 5 is at least partially interleaved with each other. To penetrate. This step forms a bond between the thermoplastic polymer implant 5 and the thermosetting polymer 2 to be cured. Due to the temperature rise during curing, the thermosetting monomers actually migrate easily to the thermoplastic polymers that make up the implant 5, in particular to their crystalline domains. According to this method, a strong bond is formed between the two. Of course, the curing temperature and time cycle are preferably selected so that the thermosetting monomer (and the curing agent) can move sufficiently deep into the melted polymer of the implant 5. Providing a thermosetting polymer 2 having a thermoplastic implant 5 may be performed without modification of the curing cycle recommended by the manufacturer for that thermosetting polymer 2. However, slight modifications may be required, particularly when the compatibility between the thermosetting polymer 2 and the thermoplastic polymer of the implant 5 is not optimal.

  According to the invention, the thermoplastic polymer (part) 4 is brought into contact with at least the surface 3 of the assembly 1, and the thermoplastic polymer and the thermosetting polymer part are heated to the melting point of the thermoplastic polymer 4, thereby The thermoplastic polymer constituting the implant 5 melts and fuses with the thermoplastic polymer (part) 4. In other words, a bond is formed between the thermoplastic polymer implant 5 and the thermoplastic polymer (part) 4, and this bond of the assembly 1 of the thermoplastic polymer 5 and the cured thermoset polymer part 2. Strengthened by cooling.

  In order to avoid excessive heating of the thermosetting polymer during the joining process, the weld area must be selected according to the geometry of the thermoplastic implant 5. In FIG. 1, the weldable area is schematically indicated by area 6. Heating this region 6 can be done at the melting point of one or both of the thermoplastic polymers 4 and 5. These polymers 4 and 5 preferably differ in melting point by 20 ° C, more preferably differ by 15 ° C, and most preferably differ by 10 ° C. Preferably, the thermoplastic polymers 4 and 5 are substantially the same polymer. The thermoplastic polymer comprising the implant 5 is preferably formed by forming a semi-interpenetrating polymer network upon curing of the thermosetting polymer 2 (shown in FIG. 1). Joined at the internal interface (as in the example shown) or joined at the external interface of the thermosetting polymer 2 (as in the example shown in FIG. 2). To achieve this objective, the thermoplastic polymer 5 is preferably compatible with the selected thermosetting monomer of the thermosetting polymer 2. Those skilled in the art of polymer science have sufficient means at their disposal, such as the well-known thermodynamic criteria and melt criteria.

  Typical joint strengths achievable with the method according to the invention are over 30 MPa, more preferably over 35 MPa, most preferably over 40 MPa (double lap joint strength test )by).

  The general welding pressure range is 50 kPa to 1 MPa, and 100 kPa to 350 kPa is recommended. However, the method according to the invention can provide a good bond even when no pressure is applied. However, pressures in excess of 1 MPa may also be used. Nonetheless, such pressure may cause some squeezing to the molten thermoplastic.

  Another embodiment of an assembly 1 of a cured thermoset polymer part 2 having a thermoplastic surface 3 that can be welded to a thermoplastic polymer part 4 according to the method of the present invention is shown in FIG. In this case, the thermoplastic polymer implant 5 is actually bonded to the outer surface of the thermosetting polymer part 2. However, according to the present invention, when the weldable region of the implant 5 is limited to the region 6, excessive heating of the thermosetting polymer at the joint with the implant 5 is avoided. Since the implant 5 is dimensioned, its function is maintained.

  The thermosetting polymer 2 with the thermoplastic polymer embedding 5 may be joined to the thermoplastic part 4 under external heat and pressure, such as a heated plate. Alternatively, even local heating elements or even heatable materials incorporated in the parts to be joined may be used to allow heat to concentrate on the weld zone 6.

  According to the method according to the invention, heating occurs above the melting point of the thermoplastic polymers 4 and 5, and these thermoplastics exhibit a substantial flow during welding even at relatively low welding pressures. This flow fills the small irregularities in the surfaces of the thermoplastics 4 and 5 or even the relatively small gap between the parts 2 and 4 to be joined.

  Yet another embodiment of an assembly 1 of a cured thermoset polymer part 2 having a thermoplastic surface 3 that can be welded to the thermoplastic polymer part 4 according to the method of the present invention is shown in FIG. In this case, the thermoplastic polymer implant 5 comprises two heat sinks 10 and 11 at the outer edges. When the weldable region is limited to region 6, so that the heating of the thermosetting polymer 2 with the implant 5 at the joint 7 is limited so as not to exceed the maximum use temperature of the thermosetting polymer, The implant 5 is dimensioned. The heat sinks 10 and 11 absorb part of the welding heat. The heat sinks 10 and 11 are attached to the implant 5 using a layer of heat absorbing paste 8. The thermosetting polymer 2 with the thermoplastic polymer implant 5 is joined to the thermoplastic part 4 by using the welding torch 9 in contact with the welded portion 4 in the contact area 6.

  FIG. 4 shows a schematic side view of a preferred implant finally used in the method of the present invention. In the embodiment shown, an implant of thermoplastic polymer is provided, comprising continuous reinforcing fibers 12 extending to the boundary (50, 51) of the implant 5. When such an implant with a thermoset polymer part solidifies, the free (dry) portions of the fibers 12 extend into the thermoset polymer, where these fiber portions are impregnated with the thermoset polymer once. Integrated with the cured thermoset polymer part. The implant according to this embodiment will prove particularly useful in the method of the invention. This is because it provides sufficient bond strength while limiting the heat applied during bonding.

  The method according to the invention further allows to remove and separate the previously welded parts 2 and 4. The parts (2, 4) are then heated at a temperature above the melting point of the thermoplastic polymer (4, 5) and both parts (2, 4) are at least partially separated, but this is not the case. The required power is only needed. Each part (2, 4) then retains most of its surface properties, and the separated parts may then be welded again according to the invented method. If necessary, additional thermoplastic material may be added to the surface of the thermoplastic material to be joined, in which case insufficient thermoplastic material can be utilized for joining.

  The assembly 1 joined according to the present invention provides improved chemical resistance, improved durability and erosion resistance, improved biocompatibility, improved friction, and such further advantages. .

  Since the invention disclosed in the detailed description is provided by way of illustration only, it will be appreciated that numerous variations are envisioned by those skilled in the art within the scope of the appended claims.

Claims (15)

a) providing a thermoplastic polymer;
b) providing a cured thermosetting polymer part, wherein the thermosetting polymer part comprises at least a portion to be joined with an implant composed of a thermoplastic polymer;
c) placing the thermoplastic polymer in contact with the at least a portion to be joined;
d) heating the thermoplastic polymer and the thermosetting polymer part to the melting point of the thermoplastic polymer at least in the contact area, whereby the thermoplastic polymer of the implant is melted and Fused with thermoplastic polymer,
e) cooling an assembly of the thermoplastic polymer and a cured thermoset polymer part such that the thermoplastic polymer joins the cured thermoset polymer part. A method of joining a thermoplastic polymer to a part, comprising:
The thermoplastic polymer has a melting point above the curing temperature of the thermosetting polymer;
The implant is designed such that heating above the maximum use temperature of the thermosetting polymer at the joint between the implant and the thermosetting polymer part is avoided during the joining step d). A method characterized by that.   The method according to claim 1, wherein the heat capacity per unit length of the implant, expressed in J / ° K / m, is greater than the heat per unit length provided to the assembly during step d).   The method according to claim 1, wherein a heat sink is applied to a portion of the implant.   The method of claim 3, wherein the heat sink is provided external to the implant.   The method according to claim 3 or 4, wherein the heat sink is provided at the outer edge of the implant.   6. A method according to any preceding claim, wherein the implant comprises reinforcing fibers that extend into the thermosetting polymer.   7. A method according to any preceding claim, wherein the thermoplastic polymer comprises a cured thermoset polymer part comprising an implant composed of the thermoplastic polymer.   The cured thermoset polymer comprising the thermoplastic implant is formed by using the uncured or partially cured thermoset polymer component having a cure temperature lower than the melting point of the thermoplastic polymer. Heating the polymer and the thermosetting polymer part to the curing temperature of the thermosetting polymer, thereby forming an uncured or partially cured thermosetting polymer part and the thermoplastic polymer constituting the implant; The method according to claim 1, which is obtained by at least partially interpenetrating.   9. A method according to any preceding claim, wherein the thermosetting polymer part comprises a fiber reinforced thermosetting polymer composite part.   10. A method according to any preceding claim, wherein the thermoplastic polymer to be joined is a thermoplastic polymer part or a part that is compatible with the thermoplastic polymer surface.   11. The thermoplastic polymer to be joined and / or the thermoplastic polymer making up the implant are selected from the class of engineering thermoplastic polymers having a melting point of at least 200 <0> C. The method described.   The thermoplastic polymer to be joined and / or the thermoplastic polymer constituting the implant is polyetherimide (PEI), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyetherketone (PEK). 12. The method of claim 11, wherein the method is selected from:, polyether ketone ketone (PEKK) and combinations thereof or equivalents thereof.   The method according to any one of claims 1 to 12, wherein the thermoplastic polymer to be joined or the thermoplastic polymer constituting the implant comprises conductive particles for local heating.   The method according to claim 1, wherein the thermosetting polymer comprises a mixture of an epoxy resin and / or a bismaleimide resin and a curing agent.   A cured thermoset polymer assembly having a thermoplastic surface and a thermoplastic polymer component welded thereto, wherein the thermoplastic polymer has a melting point above the curing temperature of the thermoset polymer. Feature assembly.

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